A heat storage device comprises a heat storage tank 2 charged with a heat
storage material 1 for storing the heat supplied from the outside, and a
heat exchanger 3 for executing an injection and an extraction of heat
between the inside of the storage tank 2 and the outside by the heat
exchange between the heat storage material and a heat transfer medium. The
heat exchanger 3 is disposed so as to execute a heat exchange between the
central portion 2a in the heat storage tank 2 and the outside, and
suppresses the natural convection of the heat storage material 1 of the
outer portion 2b by, for example, dispersing a liquid-absorbent material 5
in the outer portion 2b surrounding the central portion in the heat
storage tank 2, whereby reduces the influence of external environment on
the central portion 2a in the heat storage tank, thereby suppressing the
heat loss toward the outside.
